Undifferentiated Pleomorphic Sarcoma (UPS)

Undifferentiated pleomorphic sarcoma (UPS), previously known as malignant fibrous histiocytoma (MFH), is a common type of sarcoma, which are cancers that develop in bone or soft tissue. It generally develops in the arms and legs, but may also develop in the retroperitoneum (a space located behind the abdomen that contains many important bodily structures, such as the kidneys) and peritoneum (lining of the abdominal cavity).

When located within the bone, UPS is often confused with osteosarcoma as their cancer cells appear similar under the microscope. However, they are both distinct tumours, and can be differentiated by the presence (suggesting osteosarcoma) or absence (suggesting UPS) of osteoid (unmineralised bone tissue) cells.

UPS is slightly more common in males, and tends to be diagnosed in people over 50. However, anyone can develop this disease.

Treatment

If a UPS is detected, it will be staged and graded based on size, metastasis (whether the cancer has spread to other parts of the body) and how the cancer cells look under the microscope. Staging and grading helps your doctors determine the best treatment for you.

Cancers can be staged using the TNM staging system:

  • T (tumour) indicates the size and depth of the tumour.
  • N (nodes) indicates whether the cancer has spread to nearby lymph nodes.
  • M (metastasis) indicates whether the cancer has spread to other parts of the body.

This system can also be used in combination with a numerical value, from stage 0-IV:

  • Stage 0: this stage describes cancer cells in the place of origin (or ‘in situ’) that have not spread to nearby tissue.
  • Stage I: cancer cells have begun to spread to nearby tissue. It is not deeply embedded into nearby tissue and had not spread to lymph nodes. This stage is also known as early-stage cancer.
  • Stage II: cancer cells have grown deeper into nearby tissue. Lymph nodes may or may not be affected. This is also known as localised cancer.
  • Stage III: the cancer has become larger and has grown deeper into nearby tissue. Lymph nodes are generally affected at this stage. This is also known as localised cancer.
  • Stage IV: the cancer has spread to other tissues and organs in the body. This is also known as advanced or metastatic cancer.

Cancers can also be graded based on the rate of growth and how likely they are to spread:

  • Grade I: cancer cells present as slightly abnormal and are usually slow growing. This is also known as a low-grade tumour.
  • Grade II: cancer cells present as abnormal and grow faster than grade-I tumours. This is also known as an intermediate-grade tumour.
  • Grade III: cancer cells present as very abnormal and grow quickly. This is also known as a high-grade tumour.

Once your tumour has been staged and graded, your doctor may recommend genetic testing, which analyses your tumour DNA and can help determine which treatment has the greatest chance of success. They will then discuss the most appropriate treatment option for you.

Treatment is dependent on several factors, including location, stage of disease and overall health.

Treatment options for UPS may include:

  • Surgery, potentially including:
    • Wide en bloc resection.
    • Curettage (cancer is scraped out with a small, sharp instrument called a curette).
    • Limb-sparing surgery (surgery to remove the cancer only and salvage the limb).
    • Amputation (removal of all or part of the affected limb).
    • Bone graft (a portion of bone from another part of the body or another person is used to replace the bone lost to cancer).
  • Radiation therapy.
  • Chemotherapy.
  • Targeted therapy.
  • Immunotherapy.
  • Clinical trials.
  • Palliative care.

For more information on the treatment options, please refer to the Rare Cancers Australia Treatment Options page.

Risk factors

While the cause of UPS remains unknown, the following factors may increase the likelihood of developing the disease:

  • Older age.
  • Previous radiation therapy.

Not everyone with these risk factors will develop the disease, and some people who have the disease may have none of these risk factors. See your general practitioner (GP) if you are concerned.

Symptoms

Symptoms of a UPS may include:

  • A painless mass.
  • Swelling in affected area.
  • Swelling of affected limb (if tumour is in limb).
  • Abdominal symptoms (if in abdomen), such as:
    • Abdominal pain.
    • Loss of appetite.
    • Changes in urinary and/or bowel habits.
    • Increased abdominal pressure.
  • Weight loss.
  • Fever.
  • Fatigue.

Not everyone with the symptoms above will have cancer, but see your general practitioner (GP) if you are concerned.

Diagnosis/diagnosing

If your doctor suspects you have a UPS, they may order the following tests to confirm the diagnosis and refer you to a specialist for treatment.

Physical examination

Your doctor will collect your overall medical history, as well as your current symptoms. Following this, they may examine your body to check for any abnormalities.

Imaging & blood tests

The doctor will take images of your body using magnetic resonance imaging (MRI), a computed tomography scan (CT scan), and/or positron emission tomography (PET scan), depending on where it is suspected the cancer is. The doctor may also look at other parts of the body and looks for signs of metastasis. Additionally, a blood test may be taken to assess your overall health and help guide treatment decisions.

Biopsy

Once the location(s) of the cancer has been identified, the doctor will perform a biopsy to remove a section of tissue using a needle. The tissue sample will then be analysed for cancer cells. This can be done by a fine needle aspiration (FNA) or a core needle biopsy (CNB).

References

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